As is well known by a person skilled in the art, preloading of riser connections or pipe connections limits the tension variations in the coupling, which prolongs the lifetime of the assembly.
Patent application publication US 2008/0149390 describes a preloaded riser coupling system. In this system a misalignment between a locking profile and a facing engaging profile of a radially moveable locking member forces the two pipe elements against each other, resulting in a preload.
U.S. Pat. No. 4,708,513 describes a coupling arrangement for tubular members which provides preloading in the connections. A box and pin end of two tubular members are held together with a preload, by using a tool. Then, while being preloaded, a threaded locking ring is rotated in place on threads until it engages a torus of the pin member, locking the pin and box ends together. The preload is then removed.
Several ways to provide a preloaded connection between risers or other tubular members can be found in the prior art. However, many solutions exhibit disadvantages regarding wear, material fatigue, tolerances of dimensions, the interconnection method, etc. Thus, it is an object of the present invention to provide a coupling arrangement that avoids the drawbacks of the prior art.